Panelboard construction



T. F. BROWN ,7 9

PANELBOARD CONSTRUCTION 2 Sheets-Sheet l INVENTOR Thomas FBrown.

ATTORNEY Sept. 6, 1955 Filed Aug. 25, 1951 WITNESSES: 5% Wi// igzme Sept. 6, 1955 B ow 2,717,339

PANELBOARD CONSTRUCTION Filed Aug. 25, 1951 2 Sheets-Sheet 2 L: 1/ l 23 I I ll Q26 24 s. 3

WITNESSES: INVENTOR Thomas F. Brown.

ATTORNEY United States Patent PANELBOARD CONSTRUCTION Thomas F. Brown, Belleville, N. J.., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a cor poration of Pennsylvania Application August 25, 1951, Serial No. 243,634

16 Claims. (Cl. 317-419) My invention relates, generally, to panelboards and, more particularly, to panelboards in which a plurality of circuit interrupter devices are mounted on insulating bases in the panelboard and are selectively connected to bus-bars disposed underneath the bases.

An object of my invention, generally stated, is to provide a panelboard which shall be simple and eificient in operation and which may be economically manufactured and installed.

A more specific object of my invention is to improve the ventilation and the disposal of the arc gases from the apparatus in a panelboard.

Another object of my invention is to provide for supporting bus bars of different thicknesses in panelboards.

A further object of my invention is to provide for quickly attaching an interrupter unit to a supporting base in a panelboard.

Other objects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of my invention, a plurality of individual circuit-breaker units are mounted on an insulating base which, in turn, is mounted on a flanged metal pan adjustably mounted in a metal cabinet. Each breaker is enclosed in a separate housing which has an opening in one end for the escapement of gases produced during are interruption. The gases are permitted to rise and flow upwardly through spaces provided between the tops of barriers on the bases and cover plates for the breaker terminals. A combined terminal clip and support is provided for supporting the end of each bus bar to which an incoming power conductor is connected.

For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view, in plan, of a portion of a panelboard structure embodying the principal features of the invennon;

Fig. 2 is a view, partly in section and partly in elevation, the section being taken along the line II-II of Fig. 1;

Fig. 3 is a top plan view of one of the insulating bases utilized in the panelboard structure;

Fig. 4 is a view, in side elevation, of the base shown in Fig. 3;

Fig. 5 is a bottom plan view of the base;

Figs. 6 and 7 are enlarged views, in end and side elevation, respectively, of the combined terminal clip and bus support utilized in the panelboard structure;

Fig. 8 is a view, similar to Fig. 7, showing the terminal clip and support utilized with a thicker bus bar, and

Fig. 9 is a bottom plan view of the terminal clip. Referring to the drawings, the structure shown therein comprises a mounting plate or pan 10, a plurality of unitary bases 11 on which are mounted a plurality of circuit interrupter units 12 and a plurality of bus bars 13 for "ice conducting current to the interrupter units 12. The interrupter units 12 are preferably automatic circuit breakers of a type well known in the art. However, certain features of the invention, such as the combined terminal holder and bus bar support, may be utilized in panelboards having manually operable switches, with or without fuses, if desired.

As shown, the mounting pan 10 may be of a channel shape having outwardly extending flanges 14. The mounting pan 10 may be mounted in a suitable cabinet (not shown) in a manner well known in the art. The pan 10 may be composed of sheet metal or other suitable material.

In the present structure, each one of the bases 11 is constructed to support four circuit breaker units. It will be understood that each base may be designed to support two or any multiple of two units, if desired. The bases may be molded from a suitable insulating material.

As shown most clearly in Fig. 2, each base may be removably attached to the flanges 14 of the pan 10 by means of screws 15 which are threaded into openings provided in the flanges 14. As shown, the screws 15 extend through downwardly extending lugs 16 which, together with the upwardly extending sides of the pan 10, provide suflicient clearance between the bus bars 13 and the bottom of the pan 10 to prevent arcing between the bus bars and the pan 10.

The bus bars 13 are shown as mounted on the bottom side of the insulating bases 11 and are secured to the bases by screws 17 which extend through openings 18 provided in the' bases 11. The openings 18 are disposed in raised portions 20 formed integrally with the base 11. The screws 17 may be threaded into tapped holes provided in the bus bars 13 at regular intervals. Terminal members 19 are provided for connecting power con ductors to the bus bars 13.

As explained hereinbefore, each base 11 supports four circuit breaker units. Each of the circuit breaker units is individually enclosed by a housing 21 and is provided with an operating handle 22 which projects from an opening in the top of the housing 21.

As shown most clearly in Fig. 2, each one of the housings 21 is removably secured to a base 11 by means of a spring clip 23. The clip 23 is of a U-shape and has an L-shaped extension 24, one leg of which enters a slot 25 in the outer end of the housing 21 when the breaker unit is installed on the base 11. The inner end of the housing abuts against one of the raised portions 20 on the base.

As shown, each clip 23 is provided with two arms 24 for retaining two breaker units in position. Each clip 23 extends around the end of the base and may be attached to the base 11 by means of a screw 26 which may be of the self-tapping type. If desired, the clip may be attached to the base by means of a rivet or the clip may be of a type having a nut for the screw 26 formed integrally with the clip.

As shown in Figs. 1 and 2, the circuit-breaker units 12 are disposed side-by-side in two rows on the bases 11 with an intervening space between the inner ends of the housings 21. In the present case, only two bases 11 are shown, thereby accommodating eight circuit-breaker units. It will be understood that the number of circuitbreaker units may be increased in multiples of four by merely adding additional bases 11 to the panelbcard structure.

In order to provide for so connecting the circuit-breaker units to the bus bars 13 that the connections may be readily changed without removing the pan 10 or the circuit breakers 12 or the bases 11 from the panelboard cabinet, a cross-connecting strap 27 is provided for each oppositely disposed pair of circuit-breaker units. The

straps 27 are disposed in the space between the two rows of housings 21 and each end of the strap is connected to one terminal of a circuit-breaker unit by means of a screw 28.

Each strap is provided with three clearance holes 29, one directly over each bus bar 13. The bus bars are provided with tapped holes directly in line with the cros"- connecting straps 27. The holes 18 in the bases 11 are also in alignment with the holes in the cross-connecting straps 27 and the bus bars 13.

A strap 27 may be connected to any desired bus bar by inserting a tubular conducting member 31 in the proper hole 18 in the base 11 and then securing the strap 27 to the bus bar 13 by means of a long screw 32 which extends through the tubular member 31, as shown in Fig. 2. Thus, any desired connections may be made to the bus bars 13, that is, each pair of branch circuits may be connected to any one of the bus bars 13, thereby dividing the load between the bus bars in any desired man ner. readily changed at any time without removing the circuit-breaker units.

It will be seen that the connecting straps 27 not only conduct current to the individual circuit-breaker units but also hold one end of the units in place since the inner terminal of each breaker unit is connected. to a strap 27 by a screw 28 and the strap 27 is connected to one bus bar 13 by a screw 32 and each bus bar 13 is secured to the base 11 by one or more screws 17 which are inserted in holes 18 which are not utilized for screws 32. As shown in Fig. 1, terminal screws 33 are provided for making the desired connections to the outer terminals of the circuit-breaker units.

In order to properly insulate adjacent connecting straps 27 from each other, each one of the bases 11 is provided with an upwardly extending barrier 34 which may be formed integrally with the base 11. The barrier 34 is disposed between the two connecting straps 27 on each base 11, thereby insulating the straps from each other. As shown in Fig. l, a removable insulating plate or barrier 35 is disposed between adjacent bases 11 to insulate the straps 27 on the adjacent bases. The barriers 35 are notched in a manner similar to the barriers 34 as described hereinafter.

As shown in Figs. 1 and 2, a cover plate 36 is removably attached to each base 11 for protecting the crossconnecting straps 27. The cover plate 36 may be attached by screws 37 which are threaded into holes 38 in the barrier 34. The ends of the cover plate 36 overlap the inner ends of the breaker housings 21, thereby making it impossible to remove the breaker housings without first removing the cover plate. The sides of the cover plates overlap the barriers 35, thereby retaining them in position.

In order to provide for disposing of the arc gases from the breaker units, an opening 41 is provided in the inner end of each housing 21 for discharging the gases formed during arc interruption. As shown most clearly in Fig. 2, notches or lowered portions 42 are provided in the barriers 34 and 35 underneath the cover plates 36. Thus, the gases which are discharged through the openings 41 into the central space between the two rows of breakers are permitted to rise and flow upwardly through the spaces provided between the cover plates 36 and the tops of the barriers 34 and 35 which are reduced in height by the notches 42. In this manner, improved ventilation and flow of arc gases from the breaker units are obtained since full advantage is taken of the natural tendency of the heated gases to rise, it being understood that the panelboard is normally mounted with the pan 10 disposed vertically.

The bus bars 13 are supported at intervals along their length by being held against the under sides of the bases 11 by the screws 17 and 32, but the bases 11 do not provide sufiieient support for the projecting terminal ends Furthermore, the bussing arrangement may be of the bus bars which are subjected to large forces when the screws of the solderless lugs 19 are tightened against a heavy conductor. In order to prevent the ends of the bus bars 13 which extend below the lowest base 11 from being bent towards the mounting pan 10 when the power conductors are being connected to the terminal mem bers 19, I have provided a terminal clip 43 and an insulating support 44 shown in detail in Figs. 6 to 9. The clip 43 is of a channel shape having upwardly extending sides 45 which straddle the bus bar 13 and prevent the terminal member 19 from turning on the bus bar 13.

The clip 43 may be attached to the bus bar 13 by a bolt 46 which also attaches the terminal member 19 to the bus bar 13. As shown in Fig. 9, an elongated opening 47 may be provided in the base of the clip 43 for the bolt 46, thereby permitting the clip to be adjusted longitudinally on the bus bar 13.

The clip as is provided with downwardly extending or depending ends 48 and 49. The end 48 is of a T- shape and the end 49 is of a generally rectangular shape. As shown in Figs. 6 and 7, the insulating tube 44 may be placed on the end 48 with the top of the tube engaging the cross arms 51 of the T-shaped end 48 and the bottom of the tube resting on the mounting pan 10. Thus, the tube 44 supports the end of the bus bar 13 to prevent it from being bent downwardly when pressure is applied while making connections to the terminal member 19.

The arrangement shown in Figs. 6 and 7 is suitable for use with a bus bar 13 of a predetermined thickness. If it is desired to utilize a bus bar of a greater thickness, such as 13, and a larger terminal 19' shown in Fig. 8, the clip 43 is reversed on the bus bar 13' and the tube 44 is placed on the end 49 instead of on the end 48 of the clip. Since the end 49 does not have the shoulders or cross arms 51, the top of the tube 44 is permitted to engage the base of the clip 43, thereby compensating for the difference in thickness between the bus bar 13 and the bus bar 13. In this manner, the same clip 43 and the same insulating tube 44 may be utilized with bus bars of two different thicknesses, thereby reducing the number of parts to be carried in stock.

From the foregoing description, it is apparent that I have provided a panelboard in which all current-carrying parts are properly insulated and provision is made for improving the disposal of arc gases and the ventilation of the apparatus as compared with structures previously known. Furthermore, the individual apparatus units may be more readily installed in place on the panelboard since one end of each unit is retained in position by a spring clip and the unit may be installed or removed without it being necessary to remove the clip from the supporting base. I have also provided for preventing the ends of the bus bars being bent toward the mounting pan, thereby precluding the possibility of arcs being drawn between the bus bars and the mounting pan. The supporting arrangement is such that a minimum number of parts are required to provide panelboards having the usual commercial ratings.

Since numerous changes may be made in the abovedescribed construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a panelboard, in combination, a mounting pan, a unitary base removably secured to said pan for supporting a plurality of circuit interrupter units, said interrupter units having individual housings removably mounted on top of said base in oppositely disposed groups with an intervening space between opposite groups, each of said housings having a ventilating opening in the end thereof nearest said space, a barrier formed integrally with the base and disposed in said space longitudinally of the base, said openings being adjacent to the barrier to direct arc gases into said space, and a cover plate attached to the barrier, part of the barrier being reduced in height to provide space between the barrier and the cover plate for ventilating the housings through said openings.

2. In a panelboard, in combination, a mounting pan, a unitary base removably secured to said pan for supporting a plurality of circuit interrupter units, said interrupter units having individual housings removably mounted on top of said base in oppositely disposed groups with an intervening space between opposite groups, each of said housings having a ventilating opening in the end thereof nearest said space, a barrier formed integrally with the base and disposed in said space longitudinally of the base, said openings being adjacent to the barrier to direct arc gases into said space, and a cover plate spaced from the barrier to provide a passage for ventilating the housings through said openings.

3. In a panelboard, in combination, a mounting pan, a unitary base removably secured to said pan for supporting a plurality of circuit interrupter units, said interrupter units having individual housings removably mounted on top of said base in oppositely disposed groups with an intervening space'between opposite groups, each of said housings having a ventilating opening in the end thereof nearest said space, a barrier formed integrally with the base and disposed in said space longitudinally of the base, said openings being adjacent to the barrier to direct arc gases into said space, and cover means removably attached to the base, said cover means cooperating with the barrier to permit ventilating the housings through said openings.

4. In a panelboard, in combination, a mounting pan, a unitary base removably secured to said pan for supporting a plurality of circuit interrupter units, said interrupter units having individual housings removably mounted on top of said base in oppositely disposed groups with an intervening space between opposite groups, each of said housings having a ventilating opening in the end thereof nearest said space, a barrier formed integrally with the base and disposed in said space longitudinally of the base, said openings being adjacent to the barrier to direct arc gases into said space, and said barrier having openings therein cooperating with the openings in the housings to ventilate the housings through said openings.

5. In a panelboard, in combination, a mounting pan, a plurality of unitary bases removably secured to said pan for supporting a plurality of circuit interrupter units, said interrupter units having individual housings removably mounted on top of said bases in two parallel rows with an intervening space between the two rows of housings, each of said housings having an opening in the end thereof nearest said space, insulating barriers disposed in said intervening space, said openings directing arc gases into said space between said barriers, and cover means attached to said bases to enclose said space, said cover means being spaced from said barriers to provide a passage connecting the spaces on opposite sides of the barriers to permit flow of gases across the barriers in the space between the two rows of breakers.

6. In a panelboard, in combination, a mounting pan, a plurality of unitary bases removably secured to said pan for supporting a plurality of circuit interrupter units, said interrupter units having individual housings removably mounted on top of said bases in two parallel rows with an intervening space between the two rows of housings, each of said housings having an opening in the end thereof nearest said space, insulating barriers disposed in said intervening space, said openings directing arc gases into said space between said barriers, and cover means attached to said bases to enclose said space, said cover means being spaced from portions of said barriers to provide passages which cooperate with the openings in the housings to permit the discharge of gases from the housings.

7. In a panelboard, in combination, a mounting pan, a unitary base removably secured to said pan for supporting a plurality of circuit interrupter units, said base being spaced from said pan, said interrupter units having individual housings removably mounted on top of said base, a power conductor disposed between the base and the pan, connecting means extending through said base exteriorly of the housings for connecting the interrupter units to the power conductor, a terminal connector attached to the power conductor, a channel-shaped terminal clip straddling one end of the conductor and said terminal container, said clip having depending portions of different dimensions, and an insulating member selectively disposed on one of said portions between the clip and the pan to support the end of the conductor.

8. In a panelboard, in combination, a mounting pan, a unitary base removably secured to said pan for supporting a plurality of circuit interrupter units, said base being spaced from said pan, said interrupter units having individual housings removably mounted on top of said base, a power conductor disposed between the base and the pan, connecting means extending through said base exteriorly of the housings for connecting the interrupter units to the power conductor, a terminal connector attached to the power conductor, a terminal clip adjustably disposed at one end of the conductor and having sides straddling the conductor and the terminal connector, said clip having depending portions of different dimensions, and an insulating member selectively disposed on one of said portions between the clip and the pan to support the end of the conductor.

9. In a panelboard, in combination, a mounting pan, a unitary base removably secured to said pan for supporting a plurality of circuit interrupter units, said base being spaced from said pan, said interrupter units having individual housings removably mounted on top of said base, a power conductor disposed between the base and the pan, connecting means extending through said base exteriorly of the housings for connecting the interrupter units to the power conductor, a terminal connector at tached to the power conductor, a terminal clip disposed at one end of the conductor and having sides straddling the conductor and the terminal connector, said clip having depending ends of difierent dimensions, and an insulating tube selectively disposed on one of the ends between the clip and the pan to support the end of the conductor.

10. In a panelboard, in combination, a mounting pan, a unitary base secured to said pan for supporting a plurality of circuit interrupter units, said interrupter units having individual housings mounted on top of said base, a power conductor and connecting means for connecting the interrupter units to the power conductor, a terminal connector attached to the power conductor, a reversible terminal clip disposed at one end of the conductor, said clip having sides straddling the conductor and said terminal connector, said clip having abutments of different dimensions, and an insulating tube selectively disposed against one of said abutments between the clip and the pan to support the end of the conductor.

11. In a panelboard, in combination, a mounting pan, a base secured to said pan for supporting a plurality of circuit interrupter units, said interrupter units having individual housings mounted on top of said base, a power conductor and connecting means for connecting the interrupter units to the power conductor, a terminal connector attached to the power conductor, a reversible terminal clip disposed at one end of the conductor, said clip having sides straddling the conductor and said terminal connector, said clip having a T-shaped depending portion and a rectangular depending portion, and an insulating tube selectively disposed on one of said portions between the clip and the pan to support the end of the conductor.

12. A unitary base for supporting a plurality of op positely disposed circuit interrupter units having an intervening space between opposite units, said base having an integrally formed perpendicularly extending barrier disposed in said space, and a cover receiving portion on the top of said barrier, said portion extending above other portions of said barrier to provide ventilating passages at the top of said barrier.

13. A unitary base for supporting a plurality of oppositely disposed circuit interrupter units having an intervening space between opposite units, said base having an integrally formed perpendicularly extending barrier l disposed in said space, and support means of the top of said barrier, said barrier having notches therein adjacent to said support means to provide ventilating passages at the top of said barrier.

14. A unitary base for supporting a plurality of oppositely disposed circuit interrupter units having an intervening space between opposite units, said base having an integrally formed perpendicularly extending barrier disposed in said space, and support means on the top of said barrier, said barrier having notches therein adjacent f" to said support means, said notches being disposed at a level below the top of said support means to provide ventilating passages at the top of said barrier.

15. An insulating base for supporting a predetermined number of oppositely disposed circuit interrupter unit housings having an intervening space between opposite housings, said base having an integrally formed barrier disposed in said space and raised portions adjacent to said barrier against which one end of said housings abut, generally U-shaped metal clips extending around the ends of the base and having integrally formed L-shaped arms for engaging the other end of said housings, each clip having sufiicient arms for one half the number of housings mountable on the base, and each clip being attached to the base by retaining means extending through the legs of its U-shaped portion.

16. An insulating base for supporting a plurality of circuit interrupter unit housings having an intervening space therebetween, said base having an integrally formed barrier disposed in said space and raised portions adjacent to said barrier against which one end of said housings abut, generally U-shaped metal clips extending around the ends of the base, each clip having at least two integrally formed L-shaped arms for engaging the other ends of at least two adjacent housings, and each clip being attached to the base by retaining means extending through the legs of its U-shaped portion.

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